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(NOM0de1.)

R. M. & W. V. LOCKWOOD.

Coil for Telephones.

No. 239,261. Patented March 22,1881.

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UNITED STATES PLACE.

PATENT OFFICE.

ROBERT M.v LOOKWOOD AND WILLIAM V. LOGKVVOOD, OF NEW YORK, N. Y.,ASSIGNORS TO THE MOLECULAR TELEPHONE COMPANY, OF SAME COIL FORTELEPHONES.

SPECIFICATION forming part of Letters Patent No. 239,261, dated March22, 1881. 'Application filed October 7, 1880. (No model.)

To all whom it may concern:

Be it known that we, ROBERT M. LOOK- Woon and WM. V. LOOKWOOD, of thecity, county, and State of New York, have invented certain new anduseful Improvements in Ooils for Telephones for the Transmission ofVocal Sounds, &c., of which the following is a full, clear, and exactdescription, reference being had to the accompanying drawings, in

IQ which- Figure 1 represents our improved coil in perspective, and anarrangement of wires, showing the connection of the same with the batterreceiver, &c. Fig. 2 is a perspective view of the coil enlarged andpartly broken awayto show the half-connection of the second wire withthe wire forming the coil; and Fig. 3 is a detail view, showing one wayof forming said half-connection.

Our invention relates to a novel manner of forming or winding the coil,whereby we get a second wire, leading from the coil at a point at ornear its center, without breaking the single wire of uniform sizeforming the coil, as herein. fter explained.

The us .al method of forming the coils or helices used for telephonicand analogous purposes is w' ll understood, and need not be heredescribed.

In the construction of our coil, we take, by preference, a core ormagnet, A, and wrap the same with wire wound thereon-in the usualmanner, until the coil is about one-third (more or less) wound, the endof the wire beginning the coil projecting at a, and being connected withthe battery, as hereinafter explained. WVhen the coil is thus aboutone-third wound a second wire is attached thereto by ahalt-connectionand carried out therefrom, as shown 40 at 1), without breaking the mainwire, which is then further wound until the coil is completed,terminating in the outer end or wire, a. By this arrangement we getthree ends, a, a, and b, projected from the coil. The first named is 5shown as connecting the coil directly with the battery B, which is alsoconnected by a wire, (0 with the transmitter, (represented at D,) and bya half-connection with a wire, d, with the ground, as shown. The secondwire, I), is connected directly with the transmitter, and the third wireor end, a, of the main wire of the coil is connected with the receiver0, which, in turn, has a wire, d, connecting it with the ground.

Tracing the wire a from the receiver, through which it passes to theground on one side, it will be seen that it passes thence through theouter part of the coil to the wire I), from which point it has twodirections, constituting a split circuit, one portion going to theground through the transmitter, the other going through the inner partof the coil and the battery to the ground, thus leaving, through theconnection of the battery with the transmitter, aba-tterycircuit on theline, forming a battery telephone-circuit.

By this construction of coil we get what we term a third or telephonecurrent, dif' fering from and independent of the battery and inductioncurrents, but depending on the battery-current to produce it, and onewhich is found, in practice, to be peculiarly adapted to telephonicpurposes.

The coil may be constructed or wound in the usual way, except intheparticularspointed out, and the connections and half-connectionsdescribed may be made in the usual or any preferred form. We do notwish, therefore, to be confined to the specific form and arrangement ofthe wires in connection with the battery and the transmitting andreceiving devices, so long as the feature of the second wire introducedinto the body of the coil is preserved and a third or batterytelephonecircuit is formed through the interposition of said wire, asexplained.

hat we claim as new is 1. The magnetic coil or helix formed from asingle main wire, in combination with a second wire introduced into thebody of said coil and connected with the main wire, substantially as andfor the purpose described.

2. The combination of the magnet or core, the single main wire woundthereon and forming the coil, and the second wire introduced 5 into thebody of the coil and connected with the main wire, substantially asdescribed.

ROBERT M. LOOKWOOD. M. V. LOOIUVOOD. Witnesses:

G. H. HANKINSON, JOHN J. SToLLER.

